Cardiopulmonary exercise parameters in relation to all-cause mortality in patients with chronic heart failure

In this study we analysed the all-cause mortality over a period of maximal 6 years in 60 male patients (age: 63.4+/-8.3 years, mean+/-S.D.), suffering from chronic heart failure with resting left ventricular ejection fraction and E-./(.)O2 slope as independent factors. We assessed functional NYHA cl ass (II: n=36, III: n=24), radionuclide left ventricular ejection fraction (29.2+/-10.4%) and peak values of heart rate,(.)O2,(.)CO2,E-., anaerobic th reshold and exercise duration with an incremental work load test on the tre admill. (.)O2 relative to E-. was based on the individual slopes of the reg ression of (.)O2 on E-. during the first 6 min of exercise. These slopes wi th other exercise-related variables and factors such as etiology, medicatio n, and NYHA class were analysed with a Cox's Regression Method. A survival time analysis (Kaplan-Meier survival curve) was done to establish the influ ence of E-./(.)O2 slope and left ventricular ejection fraction (both split into above and below median values), as well as their interaction, on survi val. From all investigated exercise-related variables,E-./(.)O2 slope is th e most powerful variable regarding prediction of all-cause mortality in our group of chronic heart failure patients. Concerning risk stratification, t he subgroup (n=18) with a relatively high left ventricular ejection fractio n (>28%) and flat E-./(.)O2 slope (<27.6) had most survivors (77.8%) after about 3 years, while the subgroup (n=12) with a relatively high left ventri cular ejection fraction (>28%), but a steep E-./(.)O2 slope (>27.6) had lea st survivors (33.3%). This difference in percentage is highly significant ( P=0.0025). The fact that E-./(.)O2 slope and left ventricular ejection frac tion show comparable main and interaction effects between measures of exerc ise tolerance (e.g., anaerobic threshold, peak (.)O2, exercise duration) on the one hand, and all-cause mortality on the other, suggests the existence of common sources of variance. Based on our analysis, it is unlikely that effects on all-cause mortality are mediated through phenomena related to ex ercise tolerance. Therefore, we hypothesize that the effects on exercise to lerance and all-cause mortality both depend on common factors, which cause both cardiac and peripheral organ (c.q. muscular) dysfunctions. Moreover, t his study clearly shows that E-./(.)O2 slope during incremental exercise is an important prognostic marker for risk stratification in chronic heart fa ilure patients, NYHA class II and III. (C) 2000 Elsevier Science Ireland Lt d. All rights reserved.